WASHINGTON  The government gave the green light Tuesday to a new system designed to prevent collisions on airport runways.

The new technology, called the Airport Movement Area Safety System, uses existing airport radar to warn controllers of potential collisions.

The system has been tested at the San Francisco and Detroit airports, and is to be added to 31 other major airports between July 2001 and November 2002. Installation at the Cincinnati/Northern Kentucky International Airport is scheduled for next May.

The National Transportation Safety Board has said the system doesn't go far enough. The agency wants the FAA to develop technology that warns pilots when someone is on a runway.

The FAA's announcement comes at a time when the number of airplanes, vehicles and people erroneously entering runways is on the increase. The number of runway incursions grew from 230 in 1994 to 431 in 2000. There have been 130 accidents during the first four months of 2001, compared with 118 during the same period in 2000.